I’m currently planning a large network infrastructure for a University in Ethiopia and would like people’s comments on my planning. Please bear in mind I have never done networking before. The campus covers 80 buildings including laboratories, administration, teaching and dormitories. All buildings will have wired, wireless, VoIP and printers. Each building has 3 floors and a combination of staff and student computers.

Data centre will provide SAN storage and software PBX. Deployment is Win2k8. I am using Cisco equipment throughout the installation with include Cisco 6500 L3 core switches with 1Gbps or 10Gbps fibre connection (MM and SM) to 5 communication rooms. Each communications room also has a Cisco 6500 L3 switch. Each building is connected to the closest communications room using a 1Gbps fibre connection (MM). Each building will have a Cisco 2960 L2 switch with uplink to floor 1 and 2.

I am using vlan’s to separate the subnets as follows:

Building 1 -> VLAN 10 -> Wired computers -> - ->

Building 1 -> VLAN 11 -> Student computers -> - ->

Building 1 -> VLAN 12 -> Wireless computers -> - ->

Building 1 -> VLAN 13 -> VoIP Phones -> - ->

Building 1 -> VLAN 14 -> Printers & devices -> - ->

Building 2 -> VLAN 20 -> Wired computers -> - ->

Building 2 -> VLAN 21 -> Student computers -> - ->

Building 2 -> VLAN 22 -> Wireless computers -> - ->

Building 2 -> VLAN 23 -> VoIP Phones -> - ->

Building 2 -> VLAN 24 -> Printers & devices -> - ->

Building 80 -> VLAN 800 -> Wired computers -> - ->

Building 80 -> VLAN 801 -> Student computers -> - ->

Building 80 -> VLAN 802 -> Wireless computers -> - ->

Building 80 -> VLAN 803 -> VoIP Phones -> - ->

Building 80 -> VLAN 804 -> Printers & devices -> - ->

All buildings -> VLAN 199 -> Management&Native -> - -> I have mapped the IP address to the vlan so it’s easy to trace IP addresses to physical locations.

Questions: 1, Should I have VoIP phones all on the same vlan or separate vlan for each building as I have done above?

2, Same questions as 1 but for the printers?

3, I was planning for the Cisco 6500 L3 switches to do inter-vlan routing between vlan’s. Would this be a good solution. Would I also need a router or hardware firewall if I use L3 switch routing? My broadband input from the ISP is RJ-45 Ethernet connection.

4, Any other comment about my implementation would be appreciated as I’m a total noob at this.

Thanks in advance

  • 8
    "Please bear in mind I have never done networking before." -- How on earth did you land this contract?! Mar 27, 2011 at 11:34
  • 6
    I'm scared. Never before have the words "Hire a professional" been more apt. Mar 27, 2011 at 11:42
  • 2
    If this isn't a homework question, I think you may want re-read @Tom's comments until you hire someone else to do this.
    – jscott
    Mar 27, 2011 at 11:54
  • 7
    I'm finding it hard to understand that there's budget for all that kit, but no budget to hire someone to set it up correctly.
    – nickgrim
    Mar 27, 2011 at 13:02
  • 11
    I'm not surprised someone with no experience is doing this. Skilled workers are incredibly hard to come by in Africa. The equipment might be donated, there might have been no budget for to buy the equipment. There might be literally no money to spend on these projects. Hiring a professional might be out of the question. If this person doesn't get this done, then they have no network. Mar 27, 2011 at 13:35

4 Answers 4


I have a couple of concerns, the first is the size of your VLANs - do you really want 4k machines per VLAN in a student environment? imagine how much harder it'll be to narrow down problem machines/users in that environment, plus the number of users potentially impacted by these problem machines? I'd be tempted to go for much more smaller VLANs myself.

Secondly I'm more worried about someone who considers themselves to be a beginner designing and implementing such a comparatively large and complex network - I'd consider getting in some professionals.

  • "I'd be tempted to go for much more smaller VLANs myself" so would you suggest dividing the student vlan's into say floors (0,1,2), each having a smaller number of computers? Mar 27, 2011 at 12:18
  • I do agree on getting professionals in, but I'm a volunteer providing as much help as I can. I have assessed various companies for professional advice and to be honest, I would say I know more and cost a lot less, lol Mar 27, 2011 at 12:31
  • And I'm a lot more reliable - I hope :) Mar 27, 2011 at 13:10
  • 3
    Yes, basically, smaller vlans, i.e. break it down by floor/physical segments etc. Oh and it's nice that you're doing your best, but there really is no substitute for experience and qualification.
    – Chopper3
    Mar 27, 2011 at 13:26
  • I have added more vlan's into my design that include StaffManagement and student floors for the dormitories; will reduce the impact of hacking and virus popogation. Thanks loads for your help. I totally agree on your comment about experience, but I open to advice and am doing lots of research. Mar 28, 2011 at 16:39
  1. In my opinion, you can put them all in one vlan ( better for vlan management ), but you can also view the alternative, leaving them as you innitially designed them ( beeter for geographical management )

  2. I always split the printers in the vlans they are assigned to ( ex: the marketing dept. printer is in the marketing dept. vlan )

  3. Although it is easier to do the inter-vlan routing with a "router-on-a-stick", if you could it with you're L3 switch it will be better from a performance point of view. ( but a little harder to set up )

  4. How are you managing you're wireless vlans ? one access point per vlan ?

PS: For a begginer in networking you sure got yourself some nice equipment :)

  • Hi, thanks for your input, helps me lots. It is nice kit, I prefer the organisation purchase reliable equipment, my predecessor purchased unmanaged switches that lasted only a few months. Hoping the Cisco kit comes soon. 1, I do like the idea of seperate vlans for VoIP as I can locate the physical location from the vlan number. 2, So you would recommend putting the printers in the same vlan as the computer, simpler. 3, L3 inter-vlan is my preference, have simulated it in Packet-Tracer. 4, Was putting all the wireless AP for a single building in 1 vlan, another building uses a different vlan Mar 27, 2011 at 12:23
  • 4. Again with the wireless, what equipment are you using? how many access points are there in the network? what are the buildings made of ? Do the walls allow the radio waves to pass through ? Do the channels overlap ? Is there a need for security ? Encryption ? ( Just some more thoughts from the top of my head )
    – user76022
    Mar 27, 2011 at 18:46
  • Ok, I'm starting with 50 access points spread over 15 small buildings. Between one and two access point is used per floor. The buildings are very think concrete walls with embedder steel bars. I have worked out that radio waves will pass through 3 walls in a line. The changes will overlap between floors - is this ok? No need for security I believe, will be using RADIUS server with LDAP auth. Thanks Mar 28, 2011 at 16:59

I notice you haven't distinguished any networks/computer types by risk or by quality of service.

I would have a think about what machines on any of your networks may contain sensitive data (medical/personal/financial) and create separate VLANs for them so you can manage and audit access. Universities tend to have a culture of open and free access, but you need to look at locking down access where necessary to prevent fraud, blackmail, data destruction etc.

Also look at where your VOIP kit sits - if it is all on purely logical VLANs then make sure the QoS is set for it, otherwise when the networks are busy you will find VOIP unusable.

Update on VOIP : VOIP is much more sensitive to latency, jitter and other issues which TCP/IP is mostly immune to. Data packets can arrive at odd times, or even out of order and the TCP/IP stack rebuild the information stream pretty well. With voice traffic you notice jitter or missing packets very easily, and above a really low threshold voice traffic becomes unsuable. You can improve the quality by adding latency (to allow buffering of more packets) but this also annoys users. What QoS (Quality of Service) lets you do at the router level is prioritise time sensitive traffic at the expense of data traffic. Your data will still get through, but as it is more immune to time issues it doesn't tend to matter.

But my main comments would be - seriously, get a professional in; that is not a small network, and good luck with it, hope it goes well.

  • My original design had more vlan's to divide the sensitive data, but I was told I had to many vlans. Think I'll revert to my original vlan design then. Please could you explain "Also look at where your VOIP kit sits - if it is all on purely logical VLANs then make sure the QoS is set for it, otherwise when the networks are busy you will find VOIP unusable." Getting a professional in is not an option, the university have asked for volunteers to help. Mar 27, 2011 at 17:11
  • It's also very exciting project and a great opportunity for me and the University. I have seen other installations done by professionals out here - very badly implemented and unreliable. Thanks again. Mar 27, 2011 at 17:23
  • @Stokie - quick update on VOIP and QoS for you.
    – Rory Alsop
    Mar 27, 2011 at 21:18
  • Thanks agian for your help. I am using the L3 switch for inter-vlan routing, can I do QoS on there (Cisco 6500 Sup 720)? Mar 28, 2011 at 8:32
  • Found some information about QoS and Cisco 6500 at cisco.com/en/US/products/hw/switches/ps708/… Mar 28, 2011 at 8:41

Some references:



There are a couple of suggestions for education on these links, and reference designs.


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